Hardened nonferrous alloy



1l, R, 5, DEAN ETAL HARDBNED NONFERRGUS ALLOY Fileg O ct. 25, 1939 5 shuts-Sheet 1 C@ loo March ll, 1941. R. s. DEAN ETAL B e/fCT/zdf/Lfa@ a MM 777 Y ATTORNEYS March l1, 1941. R, Q DEAN ETAL 2,234,552

HARDENED NoNFBnnoUs ALLOY Filed Oct. 23, 1939 5 Sheets-Sheet 5 MAA MAMMNVWANW /OO 95 90 85 80 '75 70 65 60 5b' 50 l5 il u y), HMMM/ 7?? ATTORNEYS March 1l, 1941. R. s. DEAN Erm.

H'ARDENED NONFERROUS ALLOY Fild Oct.

ATTORNEYS rum ocr. 23. 1939 5 shuts-sheet 5 XML h, O* m` QN @N Om bm, Gb WD QW .0m OQ bn@ QR bh OQ mw o@ mm QQSG ATTORNEYS Patented Mar. 11, 1941 lPATENT OFFICE nAnDENEn NoNFERaoUs ALLOY Reginald S. Dean,

Washington,

D. C., and

Clarence T. Anderson, Pittsburgh, Pa., assignors to Chicago Development Company, Chicago, Ill., a corporation of Illinois Application October 23, 1939, Serial No. 300,798

8 Claims.

the metals eldsdespite the remarkable metallurgical inventions in nonferrous alloys which have been made in recent years, is their extreme versatilitycharacterized by a wide range of properties such as hardness, tensile strength, elongation and the like. Illustrative of the point raised are some of the nonferrous alloys which have gone into use to some extent such, for example, as copper-beryllium. This alloy has an advantage over the ordinary steels in that it possesses considerable corrosion resistance. I-t is, moreover, hardenable by heat treatment. The range of hardness possible with copper-beryllium, and the range of other associated properties such as tensile strength, are not suilciently great to permit its use generally for many purposes for which steel is used. It tends to be extremely 'brittle when the proportion of beryllium is increased to 21/2% and above, and in the maximum percentages of beryllium usable in a commercial alloy, namely, 2 to 21A%, the maximum hardness is in the neighborhood of Rockwell C36. Copper-beryllium is also objectionable because of its cost, the element `beryllium being extremely expensive, at the present prices, the contained beryllium in a pound of alloy not being substantially less than $1.00.

Another alloy which may be considered is copper-nickel-silicon. I'his alloy is not objectionable from the cost standpoint, since the average proportion of nickel is only about 2% and the average proportion of silicon slightly above 1%. While the-alloy can be hardened, it cannot be made tough or strong enough for many purposes, its maximum tensile strength being in neighborhood of 120,000 lbs. per square inch. The nickel sllvers are used quite extensively for certain purposes where corrosion resistance is desired, but their use is limited because they are not hardenable by any known method. Monel metals have been used to some extent, but they are expensive because of the large proportion of nickel, and ordinary Monel metals of 70% nickel-30% copper cannot be hardened. In recent years, it

has been found that an addition of a relatively small amount of certain elements to Monel metal will result in the production of alloys which are l hardenable by heat treatment. These alloys, however, do not have an adequate range of properties to permit their use generally for fabricated articles.

We have by no means discussed all of the corrosion resistant alloys which have in some part, at least, been substituted for corrodable ferrous alloys, but the above is illustrative of the need for an alloy which is corrosion resistant under the usual conditions in which fabricated articles of many kinds are used and which may, through heat treatment or a combination of cold work and heat treatment, be produced in a very wide range of properties.

We have discovered that certain alloys of copper, manganese and nickel may be produced and treated in such a manner as to make their use possible for many purposes for which there is no suitable substitute at the present time. They possess for many purposes the general properties of the corrodable ferrous alloys, but they possess the advantage of being highly resistant to corrosion under ordinary conditions to which they will be subjected during use. These alloys may have a tensile strength as low as 40,000 pounds per square inch, and as high as 250,000 or more per square inch. They have a Rockwell hardness on the C scale from as low as to as high as Rockwell'CO or above. Other properties such as elongation, ductility, machinability and the like, may correspondingly vary with the result that all of them can be readily Worked to articles of various shapes and subsequently be subjected to a controlled heat treatment to bring out exactly the range of properties desired in the final article.

For the purpose of making clear to those skilled in the art the unusual character of the alloys of our invention, we have, in the drawings, shown some of the most interesting properties of these alloys and the ranges in which these properties may occur.

In the drawings,

Fig. 1 shows the range over which the copper, nickel manganese alloys of our invention are hardenable, and illustrates increasing hardness of cold worked samples obtained by heat treatment.

Fig. 2 is a diagram similar to Fig. 1 and illustrates the electrical resistance of cold Worked alloys within the composition range identified.

Fig. 3 is similar to Fig. 2, which shows electrical resistance of the alloys as hardened by heat treatment.

Fig. 4 is a similar diagram showing the relationship between composition and temperature coefficient of electrical resistance.

Fig. 5 is a similar diagram showing the coefficient of linear expansion of some of the alloys within the range identied.

The alloys of our invention generallycan be identified as being within the shadedf area of Fig. 1. Fig. 1 is a a ternary diagram of the type commonly used by metallurgists to depict the composition and properties of alloys having three components. It will be understood that only by means of a ternary diagram oi' this character can alloys within the irregular shape of the area be represented in their entirety. As we shall point out in a subsequent part of the description, however, certain portions of the diagram and alloys of certain composition have unusually desirable properties, particularly from the standpoint. of obtaining the maximum or extreme range of properties.

The alloys of our invention show their unusual we have indicated by number the increase in hardness obtainable in the alloy c' rresponding to the point at which the number appears, by the heat treatment` of a cold worked sample which has been quenched previous to being subjected to cold work, These numbers are not indicative of the hardness, but express the increase in hardness on the Rockwell C scale. In each case, the increase in hardness was obtained by heating at a temperature of 450 degrees C. for 10 hours.

We have referred to the wide range of properties obtainable in the alloys of our invention, and in the following table We show the increase in hardness by heat treatment at various 4temperatures, together with the increase in hardness of the alloys as cast, as quenched and as cold Worked. The rst three columns identify the composition of the alloys, the next column the hardness on the Rockwell C scale as cast, iollowed by the hardness of the alloys. as quenched, as cold worked, and then when subjected to substantially the maximum hardness possible when heated to the different temperatures shown at properties in the quenched and heat treated the heads of the subsequent columns.

Table I Mn Ni Cu As cast Quenched wglgd 350 400 450 500 550 zo 2o ed -33 4o 11 23 a4 4e sa zo 15 15 70 -42 -44 6 l0 l2 19 -8 -39 35 35 30 -13 -8 +25 29 42 53 4l 18 as 45 2o -7 -9 26 2a 41 so as n as 55 1o -4 -s 21 2s a1 a7 2s s 7o so o -15 1s 15 2o 2o 21 1s s states. We have found that the maximum range of properties may be obtained by quenching from a temperature of 900 degrees C. or from any temperature above 900 degrees C. to the melting point. Intermediate mechanical working schedules aiect the properties of the alloys as well as the reheating or aging temperature to impart hardness thereto. We further found, however, that the nal hardness is not appreclably affected by the amount of coldworking nor, for that matter, is it appreciably diierent, at least within the central portion of the shaded area, when the proportions of the different constituents are modiiied. This will be illustrated hereinbelow. We do find, however, that the iinal hardness is affected by the temperature from which the alloys are quenched. If the quenched temperature is 900 degrees C. or above, the final hardness will be in general uniform. When the quenched temperature is lower, however, the nal hardening or aging step will be less effective.

It will be noted that the line marked Mn-Ni substantially bisects the shaded area, although it does run up slightly toward increased nickel content. This line corresponds substantially exactly with the hypothetical compound MnNi.

It appears therefore that the alloys of our invention may be characterized as pseudo binary alloys wherein copper is hardened by the compound MnNi. The dotted area contiguous to the nickel manganese line represents alloys which we have found diflicult to form by mechanical work. The alloys in this range are hard asv cast, and they are not easily fabricated. They do not possess the range of properties of the alloys in the shaded area, but for some purposes where they may be suitably fabricated, they may be utilized to advantage.

At `certain points in the shaded area of Fig. l,

In. Table Il following, we show the effect of heat treating quenched alloys which have not been cold worked.

It will be noted from a comparison of the two tables that there is very little diii'erence in the ultimate hardness between the alloys as cold worked and as merely quenched, except in the case of the alloy of 70% manganese, 30% nickel, included for purposes of illustration, where the hardness imparted to it is primarily that resulting from cold Work.

The tables, with the diagram of Fig. 1, are sufficiently illustrative of the general composition of the alloys of our invention, the effect of various treatments, and the relationship between composition and treatment, so that these factors need not be discussed in detail for those skilled in the art toy understand them fully. We wish to point out, however, that the maximum hardness occurs at a temperature of around 450 degrees C. and about 10 hours heating is usually suilicient to bring out the maximum hardness at this temperature. On large samples which require more time to bring up to temperature and where more than an exterior or case hardened effect is desired, it may be necessary to heat for longer periods. At about 500 degrees C. the alloys start to soften. This relationship may have an advantage for many purposes which will be A small tool parts and the like, this range is prepointed out in a subsequent portion of the specication.

We have already stated that the alloys of our invention may be considered as representative of a pseudo-binary system, namely, copper hardened with MnNi, and accordingly, we have found that the most preferable range where the maximum range oi' properties is obtainable is in that portion of the shaded area where the nickel and manganese are substantially equal, that is to say, along the pseudo-binary line CuMnNi. Accordingly, the relationship between Mn and Ni is preferably about 1 to 1, although in the range oi .8 to 1.2 or 1.2 to .8 of manganese to nickel, substantially' the same effect is obtained. This, therefore, considering the relationship of manganese to nickel is the preferred range when operating with the alloys of our invention.

From the standpoint of copper content, the range to 80% copper offers the greatest possibilities for securing the unusual results, and for general fabrication of articles such as screws,

ferred. Somewhat less corrosion resistance is obtained, but the corrosion resistance is still adequate for most purposes. When the copper is less than 50%, the corrosion resistance is increased, but the properties may not be so satisfactory from other standpoints. One of the characteristics of the alloys of our invention, as will be obvious from the tables, is that as the percentage of copper is decreased, particularly when the proportion is less than 50%, they work harden more rapidly. For many purposes, this is a disadvantage. For certain purposes, however, such as for deep drawing operations, Work hardening is desirable. Those skilled in the art, therefore, are offered a range of properties suitable for the fabrication of substantially any of the usual fabricated articles requiring relatively high strength and corrosion resistance.

In connection with the preferred proportions of the alloys of our invention, we wish particularly to call attention to the alloy of copper, 20% nickel and 20% manganese. As shown in Table I, this alloy shows a hardness of -40 on the Rockwell C scale as quenched, and a hardness of +46 on the same scale when aged at 450 degrees IC. It will be understood that minus values on the Rockwell C scale are not customarily used, but we employ them here arbitrarily to show directly the increase in hardness possible in this type of alloy. As will be pointed out later, we find in alloys oi' this type (as is the case with steel), an approximately direct relationship between hardness' and tensile strength. Thus, an. alloy of 60% copper, 20% nickel and 20% manganese. as quenched, has a. tensile strength of about 45,000 pounds per square inch. This same alloy in the fully hardened condition has a tensile strength in the neighborhood of 215,000 pounds per square inch or higher. These properties, as a skilled metallurgist will understand, are also accompanied by changes in other related properties such as elongation, ductility, machinability and the like, so that this particular alloy offers unusual possibilities for the fabrication of many different types of articles where ranges of properties are desirable; either for the purpose of facilitating manufacture or for the purpose of imparting particular properties to the finished article.

For the purpose of illustrating the characteristics of alloys falling along the pseudo-binary line or close to it, we give the following table which shows the components of the alloys,'their hardness as cast, as quenchectas cold worked and when hardened at 450 degrees C. after being quenched and cold worked. It will be noted that with up to copper, an appreciable increase in hardness isvobtained, with the most advantageous range of properties considering increase in hardness at about 60% copper,`20% nickel and 20% manganese. When the amount of copper is less than about 50%, then the proportion of hardness due to cold working gradually increases, although the ultimate hardness may be substantially the same. Furthermore, the table shows that when the relationship between nickel and manganese is varied appreciably from the ratio l to 1, the hardening effect markedly decreases.

Table III Mn N1 Cu As cast ucnched worked 4.10

10 1o so 45 4a 1 11 12,11, 12,15 75 42 4s o t 1s 15 70 41 4s 2,15 25 17 17 Gli -43 -42 6 37 20 2() (i0 -32 -40 l() 40 25 25 5() -24 -28 18 4G 22 22 se 2s as 13 4r; 3U 3() 4() -i -17 2| 50 35 35 'l0 -13 8 25 53 l 15 17in; 67% 45 43 s 21 i 2o 121/5 17A 41 42 I e 24 Table IV Tensile strength in pounds per square inch Hardness Rockwell C.

In the quenched condition, the elongation of the alloys of our invention, falling generally along the pseudo-binary line, varies between 25% and 40%. In the cold worked condition, the elongation is between 2% and 5%, while the elongation or the hardened alloys ranges from about 2% to 20%, depending upon the extent of the hardening, the composition of the alloys and the entire treatment given to them.

As disclosed in the copending application of Reginald S. Dean, Serial No. 230,209, led Septomber 16, 1938, certain alloys of manganese, includingalloys of manganese, copper and nickel, have high vibration damping capacity, at times more than times that of steel. The alloys of our present invention, however, when measured at very low stresses, have a vibration damping capacity, in general, of the order of steel, that is' to say, in the neighborhood oi' 115%. When the. proportion of manganese is increased above 65%, however, the vibration damping capacityfof the alloys as aged is of the order of 1% er more. The alloys.- of our invention show very little tendency to overage at, temperatures up to 450 degrees C. Sone of them may be heated to somewhat above this temperature without overaging, but, in general, a temperature of.450 degrees C. or belowA should be utilized for imparting the nal hardness, the exact temperature depending upon the result desired. The degree of hardening imparted to the alloys by heat treatment may also be controlled by controlling the time of treating, and graduating the time of heating at 450 degrees C. between 1 and 25 hours, depending upon the sample, will lead to good results. To obtain the maximum of hardness, usually 6 to 18 hours are required. When a temperature above 450 degrees C'. is employed, care must be taken to control the operation in order to obtain the specific desired properties.

The unusual reaction of the alloys to heating may be taken advantage of to obtain a range of hardness in a single fabricated article.v There are many cases where obtaining a range of hardness in the same article is very desirable. Nonuniform hardening may be produced by local aging of a quenched alloy, the unheated portions of the alloy being maintained at a temperature below the hardening temperature. Another manner of producing this same result is to harden the entire fabricated article and then locally heat the portion or portions thereof, which it is desired to have in a softer state, at a temperature suiilciently above the hardening temperature, to produce a softening action. Generally a temperature of 600 degrees C. will be satisfactory,` and the heat may be applied by means of a torch or in any other suitable manner. The result will be an article of graduating hardness, the softer portion generally being tougher than the hardened portion. The relatively poor heat conductivity of these alloys, together with their critical temperature of hardening and softening makes this technique of handling them very simple in the ordinary plant.

As an example of this treatment of the alloys of our invention, we wish to note an alloy containing 30%. copper, 35% manganese and 35% nickel. We have designedly taken an alloy of this particular composition because it contains less copper than the alloys previously pointed out which normally have the maximum range of properties, so that the results obtainable on an alloy of this particular composition are obtainable to the same or greater extent on the alloys containing more copper. This alloy quenched Afrom a temperature of 900 degrees C. and cold worked to a round rod 0.397 inch in diameter had a hardness on the Rockwell C scale of 25. A test sample lOl/2 inches long was employed and, after cold working, this test sample was heated to 450 degrees C. for 10 hours. 'I'he hardness of the rod was uniformly Rockwell C51. 4 inches of the rod were then heated to a red heat with a blow torch and allowed to cool in air. No special precautions were taken to maintain the unheated end cool. After this treatment a hardness determination was made at various distances/ along the rod from the heated end, and the following table shows the hardness at different distances from the soft end. As the table clearly shows, there is a. difference of 68 numbers in the Rockwell C scale, thus indicating the variation in properties which is obtainable in the same fabricated article.

Table V Distance from son. end Rockwell C All of the alloys of our invention are resistant to corrosion, those having as much as 35% nickel being resistant to corrosion by salt water. For the most part, these alloys are non-magnetic in both the quenched and aged state. 'I'he alloys containing from 20 to 35 manganese and up to 10% copper are ferro-magnetic in the aged state. 'I'he magnetism increases as the alloys approach nickel and 25% manganese in composition. The temperatures of reversible magnetic loss are lowered as the magnetism is lowered in proceeding away from this composition. From a magnetic standpoint, an alloy of 25% manganese, 70% nickel and 5% copper is interesting. Its unusual magnetic properties are exemplified by the fact that it has a substantially constant permeability of about 7 up to a eld strength of 125 oersteds.

In addition to their mechanical properties, the alloys of our invention have some unusual electrical properties. The electrical resistance of the alloys, when cold worked after quenching, is unusually high. When the alloys are heat treated to bring about hardening, however, they suffer a loss in electrical resistance over substantially the entire range, particularly along and adjacent to the pseudo-binary line. In Fig. 2, we have shown the electrical resistance of these alloys when in the quenched and cold worked state by lines of equal electrical resistance, the electrical resistance being expressed in ohms 106/cm.3. In Fig. 3, the same means is utilized to indicate electrical resistance of the hardened alloys. By consulting Figs. 2 and 3, it will be seen that along the pseudo-binary line the alloys in the quenched and cold worked state have an `electrical resistance of as high as 150, and over substantially the entire range, except at the tip corresponding to the maximum copper content, electrical resistance is at least 75. This may be compared with Fig. 3 in which over this same area the electrical resistance has decreased markedly, in no portion of the particular area pointed out, being above 70. This is bounded by an area, however, in which the electrical resistance is 100, and beyond, specifically in the direction of increased manganese, it ranges up considerably above 100. We take this distinction to be indicative of a pronounced difference in character of the alloys of our invention over somewhat related compositions of copper, manganese and nickel which have high electrical resistance and wherein the high electrical resistance is not appreciably affected by heat treatment. In other words, the profound changes in the mechanical characteristics found in the most desirable range to which our invention relates during hardening, bring about a corresponding sharp change in electrical properties, and the preferred range to which our invention relates may be characterized by reference to the electrical properties thereof in the hardened rstate. I

The electrical resistance of alloys of our invention does not change appreciably with the change in temperature; that is to say, the temperature coefilcient of electrical resistance is very low and in certain ranges is substantially zero. The coefficient of electrical resistance doesinot change appreciably when the alloys are hardened. This statement is not to ibe taken as having any bearing upon the change in specific resistance on hardening, as those skilled in the art will understand. Fig. 4 shows the relationship between composition and the coefficients of electrical resistance, the lines appearing on the graph showing those regions in which the coefficient associated with the line is the same. The temperature coeillcien-t is expressed as 10 4 ohms/ohm/deg. C.

In connection with the temperature coeclent of electrical resistance, we wish to point out, however, that, in general, such change as does occur on hardening is slightly in the direction of a positive change. An alloy of 15% manganese, ITI/2% nickel, balance copper, however, shows a movement in the negative direction on hardening, the temperature coecien-t of electrical resistance of this particular alloy when hardened, being 1.4 104 ohms/ohm/deg. C. Some alloys in this immediate vicinity show a change in the same direction on hardening.

In Fig. 5, the relationship between the linear coeilicient of expansion and the composition of the alloys of our invention is shown by means of lines identifying the alloys lying along this line as having the same coefficient of expansion. The coeiilcient of expansion is expressed as 10-6 cm./cm./deg. C. for the interval between 25 degrees C. and 100 degrees C. It will be noted that the alloys within the shaded portion (see Figure/ 1) possess wide-ly different coeiiicients of linear( expansion.

'I'he best results, so far as range of properties, particularly range of hardness and tensile strength, are obtainable in the alloys of our invention when the system consists substantially entirely and only of copper, manganese and nickel, that is to say, in which the copper, manganese and nickel are of high purity. Copper and nickel of commercial grades have, for a considerable time, been produced electrolytically, and highly pure copper and nickel are readily obtainable. The greater portion of manganese available on the market and the only manganese available until very recently has not been appreciably above manganese, the 5% not comprising manganese being represented by impurities such as iron, silicon, aluminum and carbon. In recent years, some manganese has been available in which the carbon content is relatively low, but the other impurities have not been appreciably reduced. Moreover, the impurities have, to some extent, been present a`s the oxides, and these may be particularly objectionable from the standpoint of ductility.' Silicon and iron in appreciable proportions are apt to be objectionable. We have found that electrolytic manganese is particularly adaptable for use in the alloys of our invention over the entire, range, and the hardenving and similar properties are enhanced. Moreover, the extreme range of properties obtainable in our alloys are obtained, particularly in the most useful 0f the alloys, when electrolytic manganese is used. For certain purposes, however, and in certain ranges, the alloys may be produced with less pure manganese, such as a good grado of thermit manganese. While the ductility and hardening of the alloys of our invention are affected by the use of a less pure manganese, we have found that to some extent at least, the undesirable lack of ductility obtained when a less pure grade of manganese is employed in certain ranges may be countracted by quenching from a relatively high te erature.

When we refer o the advisability of using only pure copper, nickel and manganese in the preparation of the alloys of our invention, we do not mean to say that under some circumstances and for some purposes other elements in relatively small proportions may not be used. The elements which may be so used, however, should not be the types of elements and should not be present in the form in which they are found as impurities in thermit manganese if the best resuits are to be obtained. The added elements should not appreciably affect the characteristics of the pseudo-binary system described, that is to say, the ability to obtain a range of properties as manifested by the hardening technique described. Where a fourth element may be used to impart some additional property to the alloy, Without impairing the properties described, it may be added without departing from our invention. We have found, for example, that we may add up to about 1% tin to many of the alloys of our invention without appreciable `detrimental effect upon their properties as disclosed, but with some improvement in resistance to atmospheric corrosion as well as resistance to corrosion by salt water. Ap- DrOXmately 11%% of silver added to certain of the alloys produces some advantage in the way of corrosion resistance Without sacrificing any of the mechanical properties. Small amounts of boron and silicon introduced as such, or in such a manner as to avoid the possibility of the presence of the oxides, may also be employed. While boron and silicon, by test, appear to have a slightly adverse eifect on corrosion resistance, they apv pear to improve the machinability of some of the alloys. The alloys of our invention are very easily machined, considering almost any working process to which they may be subjected, but there may be occasions where some improvement in machinability for a particular purpose may be desired.

The maximum proportion of boron and silicon which may be added without affecting appreciably the response to heat treatment has not been established definitely, but we have found that boron in amounts up to about Tn% and silicon in amounts up to about 1% may be added to many of the alloys without adversely affecting the same. When beryllium in amounts up to about 1% is added, particularly in the higher ranges of copper, hardening takes place at a somewhat lower temperature than in its absence, and for certain purposes this may be advantageous. With small proportions of beryllium the alloys are still responsive to heat treatment in the manner described. Chromium and zinc may be added in proportions somewhat greater than the other elements discussed. The addition of 10% chromium produces considerable improvement in corrosion resistance, especially in resistance to acid corrosion, and most of the alloys in the range given are responsive to heat treatment when chromium is included as a constituent. For certain purposes, we may even use very small proportions of such elements as iron and cobalt, but, in general, the use of these elements, particularly iron, is not recommended.

Because of their useful combinations of properties and the ranges in which these properties may occur, many different types of fabricated articles may be produced which heretofore have been produced from ferrous alloys and required surface finish to retard corrosion, or were made from non-ferrous alloys where corrosion resistance was essential but wherein undesirable design or other features had to be introduced to allow for insurlcient tensile strength, hardness and the like. For example, many springs which, because of the characteristics required, had to be produced from spring steel and then had to be coated subsequently to pro-tect the surface' against corrosion, can now be made with materials of our invention. Where parts are used in the presence of water, as, for example, in many places in marine work, the non-ferrous alloys used required the part to be made much larger and heavier than was convenient and desirable. Very great advantage results from the fact that even such parts as springs, requiring substantially the strength and stiffness foundonly in the ferrous alloys, may be produced readily from the alloys of our invention while they are in the soft state, and subsequent hardening will then bring out the nal desired properties. Illustrative of the kinds of parts that may be made where Various degrees of hardness may be required are non-magnetic and nonsparking tools, diaphragms, building hardware, condenser tubes, hot water tanks, pressure vessels, digesters, metal,7 furniture, bearings, dies, marine hardware and the like. In the production, for example, of molds for molding cornpounds, the alloys of our invention may be formed in the soft state by means of a master die and then heat treated. 'I'insel tape of the type used in flexible telephone cords may be produced while the alloy is soft and then heat treated to obtain the desired characteristics. In the production of nuts, bolts, screws and screw machine parts, considerable advantage is obtained in that adequate strength with corrosion resistance in parts of small size may be obtained, and simple means of manufacture are made possible. For example, in the soft state, threads may be rolled, as on screws or bolts. The alloys may be used for the manufacture of parts of equipment and machines of various types Where the use of steel is objectionable because of its magnetic properties. Where intricate machining is required, the alloys may be used to advantage because they may be machined in the soft state and subsequently hardened with a minimum of warpage and distortion. The low hardening temperature and small volume change which accompanies hardening is an advantage in the production of many fabricated parts. Of importance also is the ability to produce non-uniform hardness, in that tools and machine parts may be produced with a tough backing but with hardened working or wearing parts. Light armor plate with a tough backing and hardened outer shell may be produced. The alloys with high thermal expansion, when hardened, are useful for the production of bi-metallic strips for ternperature control purposes. In the ranges in which magnetic properties are present, the alloys may nd uses as temperature control relays on account of the low temperatures at which they lose their magnetism reversibly.

We have described our invention in considerable detail, shown their properties and indicated the manner in which these properties are of advantage in permitting the production of corrosion resistant parts where mechanical properties usually associated only with steel are required. The appended claims, however, dene the scope of the invention.

What we claim as new and desire to protect by Letters Patent of the United States is:

1. A corrosion resistantalloy consisting essentially entirely of copper, manganese and nickel, falling within the shaded 'area of Fig. 1, hardened by a quenching and aging procedure, said alloy being characterized by a substantially lower electrical resistance in the hardened state than in the quenched state.

2. A hardened corrosion resistant alloy consisting essentially entirely of substantially pure copper, manganese and nickel, the proportion of impurities being of the order of that obtained by the use of electrolytically produced alloying constituents, the alloy falling within the shaded portion of Fig. l, ther hardening resulting from y a quenching at a. temperature not substantially less than 900 degrees C. followed by aging at a temperature not substantially in excess of 450 degrees C.

3. A corrosion resistant alloy consisting essentially entirely of copper, manganese and nickel, hardened by quenching from a high temperature and reheating to a lower temperature, the proportion of manganese to nickel being not greater than 1.2 to 0.8 nor less than 0.8 to 1.2, thealloy being characterized by an abnormally large range of mechanical properties.

4. A corrosion resistant alloy consisting essentially entirely of copper, manganese and nickel, hardened by quenching from a. high temperature and reheating toa lower temperature, the proportion of manganese to nickel being not greater than 1.2 to 0.8 nor less than 0.8 to 1.2, the proportion of copper being between 50% and 80%, the alloy being characterized by an abnormally large range of mechanical properties.

5. A hardened corrosion resistant alloy consisting of copper 50% to 80%, and balance equal proportions of electrolytic manganese and nickel, the hardness resulting from a quenching of the alloy at a temperature not substantially less than 900 degrees C. followed by heating to temperatures up to approximately 450 degrees C.

6. A corrosion resistant, quenched and aged alloy consisting of 60% copper, 20% manganese and 20% nickel, the alloy being characterized by an abnormally large range of mechanical properties.

7. A corrosion resistant, quenched and aged alloy consisting essentially entirely of copper, manganese and nickel, the proportions of manganese and nickel being substantially equal, and the copper comprising between '55% and '70% of the total alloy.

8. A corrosion resistant quenched and aged alloy, having an abnormally large range of mechanical properties, consisting essentially entirely of copper, manganese and nickel, said alloy having at least 10% manganese and 10% nickel, said alloy being hardenable by quenching and aging and being characterized by markedly lower electrical resistance in the hardened state than in the unhardened state, the electrical resistance in the hardened state not being greater than 100 10 ohms/cm?.

REGINALD S. DEAN. CLARENCE T. ANDERSON. 

